Method of treatment of ligno-cellulosic material and product resulting therefrom



Sept. 27, 1949. H. w. HALL 2,483,198

METHOD OF TREATMENT OF LIGNO-CELLULOSIC MATERIAL AND'PRODUCT RESULTING THEREFROM Filed March 16, 1945 Fig. 1

A TTORNEY Patented Sept. 27; 1949 METHOD OF TREATMENT OF LIGNO-CELLU- 'LOSIC MATERIAL AND PRODUCTRESU LT ING THEREFROM Horace W. Hall, Newton, Mass, Application March 16, 1943, Serial N0. 479,386

This invention relates woods and other ligno-cellulosic substances, including vegetable cane fiber, with materials to render them fire resistant, water-proof and denser and harder than the normal state of such woods and the like.

One object is to make a highly fire-resistant article and good heat-insulatorv at a relatively low cost by using an inexpensive base or foundation board and impregnating a surface portion with an adhesive and fire-proof material that chemically re-acts therewith. 'Another object is to make said article in the form of a panel or other finished product, if desired, having a mottled design inherent in the surface that is made simultaneously with the article itself, the form of which can be varied considerably b what is done during the process of manufacture.

The finished article is a chemical re-action product of the materials entering into it having a surface portion that is non-combustible and an extraordinarily eificient heat insulator, yet hard and capable of taking high finish.

The foregoing and other objects which will appear as the nature of the invention is better understood, may be accomplished by a construction and process such as is disclosed by the drawings and specification. The nature of the invention is such as to render it susceptible to various changes and modifications, and, therefore, I am not to be limited to said disclosures; but am entitled to all such changes therefrom as fall within th scope of my claims.

In the drawings:

Figure 1 is a perspective view of the material to be impregnated. Figure 2 is a similar view after the adhesive has been applied to said material and Figure 3 is a similar view after the rock wool has been applied to said adhesive.

Figure 4 is a front elevational view showing the impregnated article under pressure between two iron plates.

Figure 5 is a front elevational view showing the said article under pressure and with heat being applied to it.

Figure 6 is a perspective view of my finished product showing the mottled effect achieved on the surface.

Reference is made to my Patent No. 2,366,025 issued December 26, 1944, because the invention herein disclosed is in part, another development of the disclosure in that application; but produc- 3 Claims. (01. 3-1155) 4 to the treatment of A 2 r conducting article and one that is less brittle, but tougher.

My process maybe illustrated by the treatment of a piece of material ll] made of vegetable cane fiber such as sugar cane fiber, which is relatively soft. There are various ligno-cellulosic materials available which may be in the form of wood, composition board and the like. Moisture content should preferably not exceed 10 to 12%.

I apply urea formaldehyde resin glue ll liberally to the surface of the article to be treated. Said glue H is preferably freshly mixed and it could -have a cold setting catalyst for quicker dehydration in the preliminary process,although that is not necessary. Said glue penetrates into the cellular structure of said piece. One ounce of glue 'to'a-square foot of the surface area to'be covered would be a suitable amount. After about fifteen minutes, if no catalyst was previously used, another coat of glue in about the same quantity should be applied with or without some well known curative catalyst, and while it is still wet, rock wool l2 or other mineral wool is applied to the wet surface at once. Said rock wool I2 is applied in quantity thick enough to absorb the free moisture of the glue so that the surface being coated is substantially dry. It is preferable to apply two coats of said glue H as described; but not necessary. Much depends upon the depth of penetration and thickness of fireproof surface portion desired. Phenol formaldehyde or other material which chemically reacts and bonds with the ligno-cellulosic fibers and with rock wool, may be used.

Smooth steel plates l4, waxed to keep them from sticking should be placed on the surfaces of the piece being treated since both surfaces are usually treated. The article is thus cold pressed between the plates with pressure sulficient to establish uniform capillarity throughout the treated portion. This pressure is preferably maintained for a substantial period of time, such as two days, for diffusion of the adhesive impregnate into the cellulosic structure of the rock wool and the treated portion of the ligno-cellulosic material. The surface coating is now somewhat soft, but smooth and dry; but not waterproof, although quite fire-proof on the surface, at least, where the rock wool is located.

The coated piece is now pressed between two hot plates l6, heated by heating elements I! and properly waxed to prevent sticking, at temperatures of 250 to 350 degrees F. for 20 to 30 minutes ing among other things a superior, non-heat with a greater pressure than before, preferably from 150 to 250 pounds to the square inch. Plasticization of the rock wool and impregnated portion of the ligno-cellulosic material with the impregnate occurs in about minutes followed by a final chemical curing and hardening of said coating materials with the treated cells of the llgnocellulosic material into an irreversibly bonded and integral rcoatingfdn the finisheilanticle which can be nailedscrewed'and is generally workable.

When an attractive design I8 is desired on the surface of the finished product, the rock wool 01" other mineral wool, or asbestospis placedennlsaid urea formaldehyde glue inmattedathmslaasersmr other sheet form preferably varying in thickness, instead of in powdered form or small fibers. The solid sheets even though small, givetthefinisheil product a mottled design i5, whereas :small particles of powdered mineral wool or the like is used the finish will be .guite plain and uniform. Of course, various color effects can be attained by :nsing well Zknnwn :enloring matter in'tthermaterials applied to the surface. Diiferentdlesigm axe achievedibyzdifierent. sizes and shapeszof'lsaid sheets, :and zby;spacingrthem :apant.

Any glue that :neacrts with neck mp1 ear other M11101 or asbestos suitable provided :it is capable of jmpregnatmg and watering rinto proper chemical reaction with ithe lights-cellulose article. Also imck :wool and :asbestos would die used together if desired as they both react with the :urea formaldehyde lglue.

What Irclaimlisz 1. A met-hedioftmanufaeture zcomprisingnppla ing :urea formaldehyde gglue "i210 lthe :surfane 11f ligno-icellulosic material, when applyingzrack'mnnl .to said glue (on said surface, :then applying :pmsvsurertosaid surfaceand 1then;a;pply-ing;lmat and greater pressure =thereto -.until said zmaterifll. 22 118 and iwoolchemically react.

REFERENCE S CITED I -he follow'ing references are of record in the filepf this patent:

UNITED STATES PATENTS Number Name "Date *ecarzo Kelly Dec.10,-1-9D'1 8855376 Ray Apr. 21,1908

*12843296 "Frederick NOV. 12, 1918 "137 05023 Kemp'ton Mar. 1, 1%?1 1,589,094 Barringer t'al. 51111635, 1926 25021348 Bekwithebal '-Nov. 19, 1 935 25366-1125 Hall Dec. '26, "1944 'FOREIGN Number iCountry )Date ?:8LQ81 @reatiBritain 1884 OTHER REFERENCES enema Met. En April ,1932 (miss, :No. 4)., pages 219 -3 12221. LC py .in .Division 

